The present invention relates to a pay television receiving system for use in cable systems or wireless broadcasting.
Pay television is operated with subscription fees paid by subscribers. In order to permit the reception of only a contracted channel, the channel selector of a receiving set has been additionally provided with a device which selectively renders the contracted channel receivable. However, there have been cases where an artifice has been applied, often in a simple manner, to enable viewing of channels that have not properly been contracted for.
In recent years, accordingly, pay television signals have been scrambled. More specifically, a video signal is put into a particular form and is scrambled by superposing a special data code signal thereon. The scrambled signal is transmitted. On the receiving side, the data code signal is decoded by a data processing circuit. A descrambler circuit restores the normal video signal after the data code signal has been decoded.